From the authors of Antispam Bee, comes this tiny plugin, that checks for, and warns you about broken links when you save a post. Simple as that. Super useful, and I’m mystified it has so few installations.
Here is a broken link for demo purposes: this-url-is-so-broken.net
And this is how the warning looks like:
Extract from WordPress.org
When a post is saved or published, this plugin will scan the post’s content for any URLs and ping all the URLs found (except relative ones), detect any broken or unreachable URLs and list them for review and correction. No more publishing of links or images broken by typos or incompletely copy-pasted URLs!https://wordpress.org/plugins/spcl/